scholarly journals When “small” terms matter: Coupled interference features in the transport properties of cross-conjugated molecules

2011 ◽  
Vol 2 ◽  
pp. 862-871 ◽  
Author(s):  
Gemma C Solomon ◽  
Justin P Bergfield ◽  
Charles A Stafford ◽  
Mark A Ratner
Keyword(s):  
Transport Properties ◽  
Single Molecule ◽  
Quantum Interference ◽  
Many Body ◽  
Conjugated Molecules ◽  
Many Body Theory ◽  
Hamiltonian Models ◽  
Single Molecule Junctions ◽  
Body Theory ◽  
Multiple Interference

Quantum interference effects offer opportunities to tune the electronic and thermoelectric response of a quantum-scale device over orders of magnitude. Here we focus on single-molecule devices, in which interference features may be strongly affected by both chemical and electronic modifications to the system. Although not always desirable, such a susceptibility offers insight into the importance of “small” terms, such as through-space coupling and many-body charge–charge correlations. Here we investigate the effect of these small terms using different Hamiltonian models with Hückel, gDFTB and many-body theory to calculate the transport through several single-molecule junctions, finding that terms that are generally thought to only slightly perturb the transport instead produce significant qualitative changes in the transport properties. In particular, we show that coupling of multiple interference features in cross-conjugated molecules by through-space coupling will lead to splitting of the features, as can correlation effects. The degeneracy of multiple interference features in cross-conjugated molecules appears to be significantly more sensitive to perturbations than those observed in equivalent cyclic systems and this needs to be considered if such supernodes are required for molecular thermoelectric devices.

scholarly journals Transmission eigenvalue distributions in highly conductive molecular junctions

2012 ◽  
Vol 3 ◽  
pp. 40-51 ◽  
Author(s):  
Justin P Bergfield ◽  
Joshua D Barr ◽  
Charles A Stafford
Keyword(s):  
Single Molecule ◽  
Effective Field ◽  
Small Contribution ◽  
Many Body ◽  
Tunneling Model ◽  
Many Body Theory ◽  
Single Molecule Junctions ◽  
Bonding Properties ◽  
Particle Nature ◽  
Body Theory

Background: The transport through a quantum-scale device may be uniquely characterized by its transmission eigenvalues τ n . Recently, highly conductive single-molecule junctions (SMJ) with multiple transport channels (i.e., several τ n > 0) have been formed from benzene molecules between Pt electrodes. Transport through these multichannel SMJs is a probe of both the bonding properties at the lead–molecule interface and of the molecular symmetry. Results: We use a many-body theory that properly describes the complementary wave–particle nature of the electron to investigate transport in an ensemble of Pt–benzene–Pt junctions. We utilize an effective-field theory of interacting π-electrons to accurately model the electrostatic influence of the leads, and we develop an ab initio tunneling model to describe the details of the lead–molecule bonding over an ensemble of junction geometries. We also develop a simple decomposition of transmission eigenchannels into molecular resonances based on the isolated resonance approximation, which helps to illustrate the workings of our many-body theory, and facilitates unambiguous interpretation of transmission spectra. Conclusion: We confirm that Pt–benzene–Pt junctions have two dominant transmission channels, with only a small contribution from a third channel with τ n << 1. In addition, we demonstrate that the isolated resonance approximation is extremely accurate and determine that transport occurs predominantly via the HOMO orbital in Pt–benzene–Pt junctions. Finally, we show that the transport occurs in a lead–molecule coupling regime where the charge carriers are both particle-like and wave-like simultaneously, requiring a many-body description.

scholarly journals Computational design of donor-bridge-acceptor systems exhibiting pronounced quantum interference effects

2016 ◽  
Vol 18 (9) ◽  
pp. 6773-6779 ◽  
Author(s):  
Natalie Gorczak ◽  
Nicolas Renaud ◽  
Elena Galan ◽  
Rienk Eelkema ◽  
Laurens D. A. Siebbeles ◽  
...  
Keyword(s):  
Charge Transport ◽  
Transport Properties ◽  
Single Molecule ◽  
Quantum Interference ◽  
Computational Design ◽  
Interference Effects ◽  
Single Molecule Junctions

Quantum interference is a well-known phenomenon that dictates charge transport properties of single molecule junctions.

On the many-body theory of nuclear reactions

1968 ◽  
Vol 111 (1) ◽  
pp. 392-416 ◽  
Author(s):  
K DIETRICH ◽  
K HARA
Keyword(s):  
Nuclear Reactions ◽  
Many Body ◽  
Many Body Theory ◽  
The Many ◽  
Body Theory

MANY-BODY THEORY FOR HYPERFINE EFFECTS IN ATOMS AND MOLECULES

1970 ◽  
Vol 31 (C4) ◽  
pp. C4-99-C4-104
Author(s):  
T. P. DAS ◽  
C. M. DUTTA ◽  
N. C. DUTTA
Keyword(s):  
Many Body ◽  
Atoms And Molecules ◽  
Many Body Theory ◽  
Body Theory

Mechanically-Tunable Quantum Interference in Ferrocene-Based Single-Molecule Junctions

2020 ◽  
Author(s):  
María Camarasa-Gómez ◽  
Daniel Hernangómez-Pérez ◽  
Michael S. Inkpen ◽  
Giacomo Lovat ◽  
E-Dean Fung ◽  
...  
Keyword(s):  
Single Molecule ◽  
Quantum Interference ◽  
Degrees Of Freedom ◽  
Building Blocks ◽  
Ferrocene Derivative ◽  
Single Molecule Junctions ◽  
Molecule Junction ◽  
Single Molecule Junction ◽  
The Impact ◽  
D Orbitals

Ferrocenes are ubiquitous organometallic building blocks that comprise a Fe atom sandwiched between two cyclopentadienyl (Cp) rings that rotate freely at room temperature. Of widespread interest in fundamental studies and real-world applications, they have also attracted<br>some interest as functional elements of molecular-scale devices. Here we investigate the impact of<br>the configurational degrees of freedom of a ferrocene derivative on its single-molecule junction<br>conductance. Measurements indicate that the conductance of the ferrocene derivative, which is<br>suppressed by two orders of magnitude as compared to a fully conjugated analog, can be modulated<br>by altering the junction configuration. Ab initio transport calculations show that the low conductance is a consequence of destructive quantum interference effects that arise from the hybridization of metal-based d-orbitals and the ligand-based π-system. By rotating the Cp rings, the hybridization, and thus the quantum interference, can be mechanically controlled, resulting in a conductance modulation that is seen experimentally.<br>

Charge Transfer Complexation Boosts Molecular Conductance Through Fermi Level Pinning

2018 ◽  
Author(s):  
Kun Wang ◽  
Andrea Vezzoli ◽  
Iain Grace ◽  
Maeve McLaughlin ◽  
Richard Nichols ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Single Molecule ◽  
Quantum Interference ◽  
Transmission Function ◽  
Scanning Tunneling ◽  
Charge Transfer Complexes ◽  
Tunneling Microscopy ◽  
Quantum Interference Effect ◽  
Single Molecule Junctions ◽  
Charge Transfer Complexation

We have used scanning tunneling microscopy to create and study single molecule junctions with thioether-terminated oligothiophene molecules. We find that the conductance of these junctions increases upon formation of charge transfer complexes of the molecules with tetracyanoethene, and that the extent of the conductance increase is greater the longer is the oligothiophene, i.e. the lower is the conductance of the uncomplexed molecule in the junction. We use non-equilibrium Green's function transport calculations to explore the reasons for this theoretically, and find that new resonances appear in the transmission function, pinned close to the Fermi energy of the contacts, as a consequence of the charge transfer interaction. This is an example of a room temperature quantum interference effect, which in this case boosts junction conductance in contrast to earlier observations of QI that result in diminished conductance.<br>

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